1. Field of the Invention
The present invention relates to an electro-optical apparatus and to a manufacturing method therefor having a structure in which a pair of substrates are bonded together via a sealing member, and also relates to an electronic apparatus using the electro-optical apparatus.
2. Description of Relared Art
In conventional electronic apparatuses such as digital steel cameras, cellular phones, personal digital assistants, personal computers, and monitors therefor, electro-optical apparatuses such as liquid crystal apparatuses and plasma display panels are widely used for displaying visible images such as numerals, characters, etc. These electro-optical apparatuses are generally formed in a panel structure in which a pair of substrates are bonded together via a roughly frame shape sealing member. A conventional liquid crystal apparatus is usually formed in a rectangular shape and in this case the sealing member has four comer portions. The bonding of the pair of substrates is achieved by curing the sealing member. As a curing method therefor, for example, UV-rays are irradiated on the sealing member.
In a conventional liquid crystal apparatus, a color filter is formed on the surface of one of the pair of substrates and a overcoat is usually formed on the color filter. The overcoat may be called a "topcoat" or an "insulating coat", and the main purposes thereof are flattening of the color filter surface and electrical insulation between the color filter and an electrode formed thereon. Since the overcoat is relatively thickly formed, it functions as a UV-ray shielding member which prevents UV-rays from passing through.
In order to prevent illuminating rays irradiated from the outside of one of the substrates from leaking to the side of the other substrate, a frame-shaped light shielding member may be formed, adjacent to the sealing member, on the surface of the opposing substrate to the substrate on which the above-mentioned overcoat is formed. The frame-shaped light shielding member is usually formed of a metal such as Cr (chromium). It is usually the case that the frame-shaped light shielding member is a UV-ray shielding member that prevents UV-rays from passing through.
As for the electro-optical apparatus such as the liquid crystal apparatus, it is recently required that the overall size be reduced. In particular, reduction in size is required for the outer-frame area, which does not contribute to the display, located outside of a viewing area where visible images such as characters are displayed.
Since the above-mentioned sealing member, the outer periphery of the overcoat, and the frame-shaped light shielding member are included in the aforementioned outer-frame area, reducing the outer-frame area results in reducing the distance between the sealing member and the overcoat, and the distance between the sealing member and the frame-shaped light shielding member.
Generally, UV-rays for curing the sealing member are irradiated from the side of the substrate on which the color filter is formed, that is, the substrate on which the overcoat is coated. Since the overcoat generally is a UV-ray shielding member, when the distance between the sealing member and the overcoat is reduced by reducing the outer-frame area of the liquid crystal apparatus as described above, the UV-rays irradiated from outside of the substrate are not sufficiently supplied to the sealing member, shielded by the overcoat so that the sealing member is not sufficiently cured. This results in degradation of the liquid crystal apparatus by the reaction between the non-cured portion of the sealing member and the liquid crystal.
In view of the other substrate opposing to the substrate on which the color filter is formed, when the outer-frame area of the liquid crystal apparatus is reduced, the distance between the sealing member and the frame-shaped light shielding member, both included in the outer-frame area, is also reduced. Assuming that the sealing member and the frame-shaped light shielding member overlap at a position, the sealing member protrudes onto the surface of the frame-shaped light shielding member and may further extend along the surface toward the inside of the liquid crystal apparatus. If the sealing member extends toward the inside in this manner and enters into the region where the overcoat formed on the opposing substrate exists, when UV-rays are irradiated from the overcoat side, the sealing member located in a region behind the overcoat remains in a non-cured state. This also results in degradation by the reaction between the non-cured portion of the sealing member and the liquid crystal.
FIG. 10 shows an enlarged corner portion of the liquid crystal apparatus. As shown in the drawing, it may be a common case that at the comer portion "A" of the sealing member 102, the sealing member 102 more often approaches the overcoat 103 on the substrate 101b on which the overcoat 103 formed thereon, compared with that in the straight portion of the sealing member 102. On the substrate 101a opposing the overcoat-side substrate 101b, the sealing member 102 approaches the frame-shaped light shielding member 106 at the comer portion "A" on more occasions than those in the straight portion of the sealing member 102.
The reasons the sealing member 102 approaches the overcoat 103 at maximum at the comer portion "A" and the sealing member 102 approaches the frame-shaped light shielding member 106 at maximum at the same comer portion "A" generally are that, in a conventional liquid crystal apparatus, the comer portions of the overcoat 103 and the frame-shaped light shielding member 106 are pointedly formed in a roughly rectangular shape, and that the sealing member 102 tends to be broad in its width at the comer portion "A".